The present invention concerns an operating device for installation in a steering wheel of a motor vehicle with a mounting frame and an optical finger navigation module.
From the publication EP 2 369 818 A1, an optical finger navigation module for a mobile telephone is known. It is surrounded by an annular illuminated area and possesses a chrome-like ring for better orientation for the user.
An optical finger navigation module (OFN) can be integrated as a sensor for the detection of finger movements in the switch block of a motor vehicle steering wheel. Control signals obtained from this can be used for example to control a display menu in the motor vehicle. In many cases, this kind of OFN can also be embodied as a button or push switch, and therefore can be activated at right angles to the operating area (switch panel).
For better orientation, it is advantageous if the finger navigation module has an illumination. An annular illumination has proven to be expedient to this end. In a qualitatively high-value embodiment, the annular illumination should be homogeneous and be available in various embodiments. A further requirement regarding practicability when using the vehicle steering wheel is that the OFN used as a button or switch should have activation haptics comparable to that of a short-stroke button. Furthermore, it is desirable if the operating area of the OFN has a close-tolerance overlap to the surrounding switch panel. Moreover, the movements of the OFN should not result in deterioration of the contacts of the OFN to the printed circuit board. It would be desirable, furthermore, if the fixing of the OFN could be carried out without gluing.
In so-called “consumer electronics” today, OFN 1 is used, as is shown in the plan view of FIG. 1 and the side view of FIG. 2. This kind of OFN 1 has a quadratic operating area 2, for example. This is surrounded by an illumination ring 3, the surface of which is flush with that of the operating area. The illumination ring 3 is therefore integrated into the OFN 1. It is applied e.g. by means of PVD (physical vapor deposition), so that it functions like a chrome surface in the unilluminated state during the day. At night time the illumination ring 3 is illuminated.
A snap disk 4 is glued on the module underside of the OFN 1. It functions as a button element. The integration of the illumination ring 3 and the snap disk 4 into the OFN 1 is motivated by the desire in consumer electronics for minimal construction depth. However, this embodiment has numerous disadvantages, which oppose the use of this kind of OFN 1 in a motor vehicle steering wheel.
Due to the small construction depth, the integrated ring illumination cannot be embodied homogeneously, as the gap from the illuminating LED to the surface to be illuminated is too small. The difference in brightness inside the ring illumination amounts to up to 50 percent, which is not enough for the quality requirements in a vehicle.
Due to the integration of the illumination, the OFN in the area to be illuminated additionally needs to have a translucent surface, which is not yet suitable for automotive use according to the current prior art. For example, this surface cannot withstand the temperatures and humidities that are normal in the automotive sector.
A third disadvantage is that color variations in the illumination always lead to a change in the OFN itself. This opposes the desire, which is conventional in the automotive sector, to differentiate different vehicle classes and equipment lines from each other using a variation of illumination colors and the use of decorative elements, while at the same time using technical components that are as unchanged as possible.
With the snap disk glued on, the operating forces and paths necessary for using the vehicle cannot be shown. In order to avoid unintended operation in all driving situations, and to avoid vibrations that could thereby possibly arise, in the vehicle the operating forces must be higher, and the operating paths longer, than in consumer electronics. This in turn necessitates good guiding of the OFN, which is not possible using the low construction depths in consumer electronics.
The object of the present invention therefore consists in providing an operating device with an optical finger navigation module for installation in a steering wheel of a motor vehicle, which meets the requirements in vehicle construction.
An operating device for installation in a steering wheel of a motor vehicle with a mounting frame and an optical finger navigation module is therefore provided. In the mounting frame, a first light guiding element and the optical finger navigation module are held by a light sealing element. The light sealing element is fastened by means of a snap connection to the mounting frame, and the mounting frame has at least one guide element, with which a movement of the mounting frame can be guided.
Advantageously, therefore, a mounting frame and a light sealing element are mounted to each other almost as housing by a snap connection, and the optical finger navigation module and a light guiding element is thereby held in their interior. The light sealing element therefore has an additional holding function, as is typical for a housing. Furthermore, the mounting frame also has a guide element, on which the operating device can be guided when moving. With this, the mounting frame also has the function of movement guiding, alongside its holding function.
A second light guiding element is preferably inserted between the optical finger navigation module (OFN) and the light sealing element. This has the advantage that the first light guiding element can be optimized with regard to light distribution, while the second light guiding element can be optimized with regard to the color, for example, and can be kept easy to change.
The first light guiding element and the second light guiding element can each be designed in the shape of a ring and can surround the optical finger navigation module. Using a ring illumination made possible by this, the user of the operating device can orient himself or herself optically, and locate the operating area of the optical finger navigation module more easily.
It is furthermore advantageous if a rubber-elastic element is arranged between the optical finger navigation module and the mounting frame. This element, also known as a soft component, can also serve both the tolerance equilibrium and the strain relief of the elastic connections of the OFN.
Specifically, the rubber-elastic element can press an electric conductor, in particular a foil conductor, of the optical finger navigation module to the strain relief on the first light guiding element. To this end, the rubber-elastic element can be designed to be disk-shaped and appropriately contoured.
Specifically, a contactor can be prepared for mounting in a steering wheel having an operating device described above and at least one further operating device. In this way switch blocks, such as are conventional in modern steering wheels, can be implemented having the operating device according to the invention.
The contactor can be equipped with a housing, in which the operating devices are installed and which has a guide element corresponding to the guide element of the mounting frame, for guiding the mounting frame in the housing. In this way a closed module can be prepared, which can be installed in a steering wheel in a few steps.
Furthermore, at least one light source can be arranged in the housing, the light from which is guided over the first and second light guiding element onto the surface of the operating device. In this way, the operating device itself is therefore free from light sources, and it is nevertheless illuminated on its surface.
Furthermore, a switch tower of a switch is arranged on the side of the mounting frame facing away from the optical finger navigation module, which can be activated by moving the mounting frame. In this way, the operating device having the optical finger navigation module can be used at the same time as an activation element for a switch.
In a further embodiment, a safety mat is arranged on the side of the mounting frame facing away from the optical finger navigation module, which presses the conductor of the optical finger navigation module to the strain relief against a section of the housing. In this way the safety mat, which is typically made of an elastic material (e.g. silicon), additionally takes on the function of a strain relief.
The present invention is now described in greater detail by means of the attached drawings.